User Manual

3.0 Calibration
The 7880-A has a single adjustment – the Crystal Oscillator frequency. In order
to adjust the Crystal Oscillator frequency, a suitable frequency counter must be attached
to the antenna port. With the 7880-A set to transmit, using Manchester coding, the
Crystal Oscillator may be adjusted until the average frequency measured by the
frequency counter corresponds to the desired center frequency. The average frequency
should be set to within 300 Hz of the desired value. Note: The frequency counter must
be capable of measuring up to 470 MHz with an accuracy of 100 Hz in order to ensure
proper calibration of the 7880-A.
4.0 Device Programming
The operation of the 7880-A is controlled by the Programming Port. The protocol
conforms to the Serial Peripheral Interface (SPI), originated by Motorola. The interface
operates in a full duplex manner, with data shifted into the PDI pin at the same time as
data is shifted out on the PDO pin. Data transfer cycles are initiated by the low-going
transition of the PSEL pin; individual data bits are synchronized to the PCLK pin.
5.0 Data Communication
The DIO pin is bidirectional. When the 7880-A is in transmit mode, the DIO pin
becomes an input for the data to be transmitted. When the 7880-A is in receive mode, the
DIO pin becomes an output. In both cases, the data is synchronized to the DCLK pin.